Third and fourth generation mobile telecommunication systems, such as those based on the 3GPP defined UMTS and Long Term Evolution (LTE) architecture are able to support more sophisticated services than simple voice and messaging services offered by previous generations of mobile telecommunication systems.
For example, with the improved radio interface and enhanced data rates provided by LTE systems, a user is able to enjoy high data rate applications such as mobile video streaming and mobile video conferencing that would previously only have been available via a fixed line data connection. The demand to deploy third and fourth generation networks is therefore strong and the coverage area of these networks, i.e. geographic locations where access to the networks is possible, is expected to increase rapidly.
The anticipated widespread deployment of third and fourth generation networks has led to the parallel development of a class of devices and applications which, rather than taking advantage of the high data rates available, instead take advantage of the robust radio interface and increasing ubiquity of the coverage area. Examples include so-called machine type communication (MTC) applications, which are typified by semi-autonomous or autonomous wireless communication devices (i.e. MTC devices) communicating small amounts of data on a relatively infrequent basis. Examples include so-called smart meters which, for example, are located in a customer's house and periodically transmit information back to a central MTC server data relating to the customers consumption of a utility such as gas, water, electricity and so on. Other examples include medical devices and automotive applications in which measurement data is gathered from sensors on a vehicle and transmitted via a mobile communications network to a server attached to the network.
Unlike a conventional third or fourth generation communications device such as a smartphone, an MTC-type terminal is preferably relatively simple and inexpensive, having a reduced capability. It is usually justified to include complex transceivers in a smartphone because a smartphone will typically require a powerful processor to perform typical smartphone type functions. However, a desire to use relatively inexpensive and less complex devices to communicate using LTE type networks may result in a receiver of such a device to be less sensitive to detect and to recover data from received signals or a transmitter may be less powerful. Furthermore, MTC devices may deployed in locations where it may be more difficult for radio signals to reach the device, for example, in a situation in which a communications device such as a smart meter is deployed in the basement of a house.
In order to improve a likelihood that radio signals may be received by a low cost communications device or from a low cost communications device, it has been proposed to deploy a so called extended coverage cell or an enhanced wireless access interface. Cell enhancement or extension is a technique which is being proposed for example for LTE Standards which provides an arrangement of effectively extending a coverage area of a base station or eNodeB to reach a communications device which may be otherwise out of a coverage area. Coverage extension is achieved by employing a wireless access interface enhancement techniques such as boosting the power of certain signals or transmitting control signals or data repeatedly, effectively a coverage area of the base station can be extended.
In a scenario in which a communications device must select or reselect a wireless access interface provided by a base station to form a cell of a mobile communications system, it will be appreciated that there may be occasions when it is appropriate to select an extended coverage cell, whereas in other situations the extended coverage cell may not provide an optimum use of communications resources.